HELP!

I want to enter a letter in cell C2 and upon pressing ENTER on the keyboard
get Excel to return a value into cell C2 (depending on the letter entered in).

A = 12
B = 10
C = 8
D = 6
E = 4
F = 2
U = 0

I have tried using a VLOOKUP but because I want to enter A and receive 12 in
the same cell I keep ending up with circular references - help!!!

Thanks

Sarah